1. Field of the Invention
The present invention relates generally to a touch display device, and more particularly to a touch display device, in which printed circuit layer is coated on the display surface of the liquid crystal display unit so that the cost for the circuit boards is saved. Furthermore, the displacement of the touch point can be avoided to maintain the touch precision.
2. Description of the Related Art
Along with the continuous advance of sciences and technologies, there is a trend in the commercially available electronic products to have smaller and smaller volume, while larger and larger screen. Such electronic product generally is free from any operation pushbutton and has a touch screen for a user to directly operate the electronic product.
Infrared touch control technique is the most popular technique for the existent large-size touch screens. The infrared touch screen basically includes a touch substrate and multiple transmitters and multiple receivers mounted on a periphery of the touch substrate in a certain sequence. The transmitters and receivers are one-to-one correspondingly arranged to form a tidily interlaced infrared ray network. That is, a perpendicular transmission/receiving array is formed along the periphery of the touch substrate. Under the control of a processor, the corresponding transmitters and receivers are respectively connected in a certain sequence to detect whether the infrared rays between the corresponding transmitters and receivers are interrupted so as to judge whether a touch takes place.
Please refer to FIG. 1. The conventional touch panel detection device 1 includes a frame 10 and multiple circuit boards 11 fixedly disposed on an inner side of the frame 10. Multiple transmitters 111, multiple receivers 112 and multiple electronic components 113 are arranged on the circuit boards 11. The transmitters 111 and receivers 112 are such arranged as to form an infrared touch matrix. The circuit boards 11 are positioned on a liquid crystal display unit 12 enclosed in a case 13. Under the control of the electronic components 113, the corresponding transmitters 111 and receivers 112 are respectively connected in a certain sequence to detect whether the infrared rays between the corresponding transmitters 111 and receivers 112 are interrupted so as to judge whether a touch takes place. Multiple circuit boards 11 are arranged on the frame 10 and electrically connected with each other. The cost for the circuit boards 11 is quite high so that the manufacturing cost of the touch panel is increased. Moreover, the circuit boards 11 cause increase of thickness of the touch panel and inconvenience in installation.
Furthermore, it is uneasy to locate the circuit boards 11 on the liquid crystal display unit 12. The circuit boards 11 are fixed with the frame. When moving the screen, the liquid crystal display unit 12 tends to displace within the case 13. In this case, the touch position detected by the transmitters 111 and receivers 112 is likely to displace from the picture displayed on the liquid crystal display unit 12. As a result, the touch point is displaced and the touch precision is deteriorated.
According to the above, the conventional technique has the following shortcomings:
1. The cost for the circuit boards is quite high so that the manufacturing cost of the touch panel is increased.
2. The circuit boards cause increase of thickness of the touch panel.
3. The circuit boards cause inconvenience in installation.
4. The touch precision is deteriorated.